The average investor can find compelling investment ideas by looking at what the big boys are doing. Regulations require larger asset managers to disclose their holdings every quarter, which can provide valuable insights into potential stocks to buy.

Hey, you looking for a place on Manhattan's Upper West Side?Well, if you've got $20 million, Bill Ackman might be able to help you.Related: Billionaire Bill Ackman buys 3 million shares of battered consumer stockThe billionaire hedge fund manager has listed two neighboring apartments for a total of $19.

Pershing Square bought roughly 25.9 million shares of Brookfield in Q3, increasing its stake by almost 378%. Brookfield is a dividend stock, but I doubt there's an income investor on the planet who would get excited about the company's dividend.

Over the last two quarters, Ackman has built two new significant positions for Pershing Square -- Nike ( NKE 3.06%) and Brookfield ( BN 1.29%) -- piling an estimated $2.2 billion into those stocks during the third quarter alone. Here's why.